the u.s. loses a warplane as the allies keep up the assault on libya and qaddafi remains defiant. >> ( translated ): we will win. we will be victorious in this historical battle. we will not surrender. >> couric: i'm katie couric. also tonight, they survived one disaster, now these japanese have been forced to take shelter against another threat: nuclear radiation. america's nuclear problem. where to store permanently more than 145 million pounds of spent fuel rods. and college students struggling to make the grade. what some schools are doing to make sure they graduate. captioning sponsored by cbs from cbs news world headquarters in new york, this is the "cbs evening news" with katie couric. >> couric: good evening, everyone. it's four days into a u.s.-led assault on his military, and libya's moammar qaddafi has lost radar installations, tanks, and naval facilities but not his defiance. he appeared in public tonight in tripoli vowing to fight on and telling supporters he will win and will not